Wave energy distribution at inlet channel margins as a function of ebb tidal delta morphology: Cananéia Inlet, São Paulo, Brazil

Abstract

Wave energy gradients between and along the margins of inlet channels play an important role in defining the inlet margins’ evolutionary processes, mainly those related to spit erosion or accretion, and inlet migration. The aim of this study is to understand the wave power distribution along the margins of a tidal inlet (Cananéia inlet, São Paulo, Brazil), its variation over time, and the influences of the ebb tidal delta morphology on the incoming waves. To evaluate changes in bathymetry and morphology of submersed features, we apply geoprocessing techniques to analyze nautical charts from the Brazilian Navy from 1939, 1971, 1985 and 2004. The numerical model MIKE21 SW was applied to assess wave propagation and nearshore wave power. Hence, wave energy levels along the inlet margins were assessed in terms of decadal morphological changes. The results indicate a dynamic behavior of the inlet and ebb tidal delta, pointing to the ebb tidal delta as the main transforming agent of the waves that reach the inner portion of the channel. The morphological changes of the ebb tidal delta over the last decades are critical to define the action of waves on the margins of the inlet.